Advanced Technologies in Radiation Research.

The U.S. Government is committed to maintaining a robust research program that supports a portfolio of scientific experts who are investigating the biological effects of radiation exposure. On August 17 and 18, 2023, the Radiation and Nuclear Countermeasures Program, within the National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), partnered with the National Cancer Institute, NIH, the National Aeronautics and Space Administration, and the Radiation Injury Treatment Network to convene a workshop titled, Advanced Technologies in Radiation Research (ATRR), which focused on the use of advanced technologies under development or in current use to accelerate radiation research. This meeting report provides a comprehensive overview of the research presented at the workshop, which included an assembly of subject matter experts from government, industry, and academia. Topics discussed during the workshop included assessments of acute and delayed effects of radiation exposure using modalities such as clustered regularly interspaced short palindromic repeats (CRISPR) - based gene editing, tissue chips, advanced computing, artificial intelligence, and immersive imaging techniques. These approaches are being applied to develop products to diagnose and treat radiation injury to the bone marrow, skin, lung, and gastrointestinal tract, among other tissues. The overarching goal of the workshop was to provide an opportunity for the radiation research community to come together to assess the technological landscape through sharing of data, methodologies, and challenges, followed by a guided discussion with all participants. Ultimately, the organizers hope that the radiation research community will benefit from the workshop and seek solutions to scientific questions that remain unaddressed. Understanding existing research gaps and harnessing new or re-imagined tools and methods will allow for the design of studies to advance medical products along the critical path to U.S. Food and Drug Administration approval.

National Cancer Institute Collaborative Workshop on Shaping the Landscape of Brain Metastases Research: challenges and recommended priorities.

Brain metastases are an increasing global public health concern, even as survival rates improve for patients with metastatic disease. Both metastases and the sequelae of their treatment are key determinants of the inter-related priorities of patient survival, function, and quality of life, mandating a multidimensional approach to clinical care and research. At a virtual National Cancer Institute Workshop in September, 2022, key stakeholders convened to define research priorities to address the crucial areas of unmet need for patients with brain metastases to achieve meaningful advances in patient outcomes. This Policy Review outlines existing knowledge gaps, collaborative opportunities, and specific recommendations regarding consensus priorities and future directions in brain metastases research. Achieving major advances in research will require enhanced coordination between the ongoing efforts of individual organisations and consortia. Importantly, the continual and active engagement of patients and patient advocates will be necessary to ensure that the directionality of all efforts reflects what is most meaningful in the context of patient care.

Radiation-induced pulmonary fibrosis: roles of therapy-induced senescence and microRNAs.

PURPOSE: Progressive, irreversible radiation-induced pulmonary fibrosis (RIPF) is a clinically significant intermediate- to a late-occurring side effect of radiotherapy. Known mechanisms of RIPF include oxidative stress-induced activation of TGF-ß with activation of SMAD signaling, TNF-α elaboration, and activation of the Angiotensin Converting Enzyme (ACE) mediated production of angiotensin II with resulting activation of profibrotic cytokine signaling and vasoconstriction. The pioneering work of John Moulder, to whom this paper is dedicated, and several of his colleagues demonstrated that inhibiting the conversion of ACE with drugs such as Captopril, Enalapril, and Losartan can ameliorate radiation fibrosis in various tissues. While this work led several groups to probe mechanism-based pharmacological mitigation of RIPF, in this article, we explore and discuss the roles of microRNAs (miRNA) and therapy-induced senescence (TIS) in the pathogenesis of and potential biomarkers for RIPF. CONCLUSION: Our analysis of the published literature in the last decade on RIPF, miRNA, and TIS identifies TIS as a mechanism in the onset and progression of RIPF, which is regulated through several miRNAs. This work may lead to the discovery and development of the next generation of miRNA therapeutics and/or the repurposing of approved pharmaceutical agents and the development of early biomarker panels to predict RIPF.

Inter-agency perspective: Translating advances in biomarker discovery and medical countermeasures development between terrestrial and space radiation environments.

Over the past 20+ years, the U.S. Government has made significant strides in establishing research funding and initiating a portfolio consisting of subject matter experts on radiation-induced biological effects in normal tissues. Research supported by the National Cancer Institute (NCI) provided much of the early findings on identifying cellular pathways involved in radiation injuries, due to the need to push the boundaries to kill tumor cells while minimizing damage to intervening normal tissues. By protecting normal tissue surrounding the tumors, physicians can deliver a higher radiation dose to tumors and reduce adverse effects related to the treatment. Initially relying on this critical NCI research, the National Institute of Allergy and Infectious Diseases (NIAID), first tasked with developing radiation medical countermeasures in 2004, has provided bridge funding to move basic research toward advanced development and translation. The goal of the NIAID program is to fund approaches that can one day be employed to protect civilian populations during a radiological or nuclear incident. In addition, with the reality of long-term space flights and the possibility of radiation exposures to both acute, high-intensity, and chronic lower-dose levels, the National Aeronautics and Space Administration (NASA) has identified requirements to discover and develop radioprotectors and mitigators to protect their astronauts during space missions. In sustained partnership with sister agencies, these three organizations must continue to leverage funding and findings in their overlapping research areas to accelerate biomarker identification and product development to help safeguard these different and yet undeniably similar human populations - cancer patients, public citizens, and astronauts.

The State of Preclinical Modeling for Early Phase Cancer Trials Using Molecularly Targeted Agents with Radiation.

Preclinical studies inform and guide the development of novel treatment combination strategies that bridge the laboratory with the clinic. We aimed to evaluate approaches cancer researchers used to justify advancing new combinations of molecularly targeted agents and radiation treatment into early-phase human clinical trials. Unsolicited early phase clinical trial proposals submitted to the National Cancer Institute's Cancer Therapy Evaluation Program between January 2016 and July 2020 were curated to quantify key characteristics and proportion of preclinical data provided by trialists seeking to conduct molecularly targeted agent-radiation combination studies in cancer patients. These data elucidate the current landscape for how the rationale for a molecularly targeted agent-radiation combination therapy is supported by preclinical research and illustrate unique challenges faced in translation at the intersection of precision medicine and radiation oncology.

Moving Forward in the Next Decade: Radiation Oncology Sciences for Patient-Centered Cancer Care.

In a time of rapid advances in science and technology, the opportunities for radiation oncology are undergoing transformational change. The linkage between and understanding of the physical dose and induced biological perturbations are opening entirely new areas of application. The ability to define anatomic extent of disease and the elucidation of the biology of metastases has brought a key role for radiation oncology for treating metastatic disease. That radiation can stimulate and suppress subpopulations of the immune response makes radiation a key participant in cancer immunotherapy. Targeted radiopharmaceutical therapy delivers radiation systemically with radionuclides and carrier molecules selected for their physical, chemical, and biochemical properties. Radiation oncology usage of "big data" and machine learning and artificial intelligence adds the opportunity to markedly change the workflow for clinical practice while physically targeting and adapting radiation fields in real time. Future precision targeting requires multidimensional understanding of the imaging, underlying biology, and anatomical relationship among tissues for radiation as spatial and temporal "focused biology." Other means of energy delivery are available as are agents that can be activated by radiation with increasing ability to target treatments. With broad applicability of radiation in cancer treatment, radiation therapy is a necessity for effective cancer care, opening a career path for global health serving the medically underserved in geographically isolated populations as a substantial societal contribution addressing health disparities. Understanding risk and mitigation of radiation injury make it an important discipline for and beyond cancer care including energy policy, space exploration, national security, and global partnerships.

Therapy-Induced Senescence: Opportunities to Improve Anticancer Therapy.

Cellular senescence is an essential tumor suppressive mechanism that prevents the propagation of oncogenically activated, genetically unstable, and/or damaged cells. Induction of tumor cell senescence is also one of the underlying mechanisms by which cancer therapies exert antitumor activity. However, an increasing body of evidence from preclinical studies demonstrates that radiation and chemotherapy cause accumulation of senescent cells (SnCs) both in tumor and normal tissue. SnCs in tumors can, paradoxically, promote tumor relapse, metastasis, and resistance to therapy, in part, through expression of the senescence-associated secretory phenotype. In addition, SnCs in normal tissue can contribute to certain radiation- and chemotherapy-induced side effects. Because of its multiple roles, cellular senescence could serve as an important target in the fight against cancer. This commentary provides a summary of the discussion at the National Cancer Institute Workshop on Radiation, Senescence, and Cancer (August 10-11, 2020, National Cancer Institute, Bethesda, MD) regarding the current status of senescence research, heterogeneity of therapy-induced senescence, current status of senotherapeutics and molecular biomarkers, a concept of "one-two punch" cancer therapy (consisting of therapeutics to induce tumor cell senescence followed by selective clearance of SnCs), and its integration with personalized adaptive tumor therapy. It also identifies key knowledge gaps and outlines future directions in this emerging field to improve treatment outcomes for cancer patients.

Normal Tissue Injury Induced by Photon and Proton Therapies: Gaps and Opportunities.

Despite technological advances in radiation therapy (RT) and cancer treatment, patients still experience adverse effects. Proton therapy (PT) has emerged as a valuable RT modality that can improve treatment outcomes. Normal tissue injury is an important determinant of the outcome; therefore, for this review, we analyzed 2 databases: (1) clinical trials registered with ClinicalTrials.gov and (2) the literature on PT in PubMed, which shows a steady increase in the number of publications. Most studies in PT registered with ClinicalTrials.gov with results available are nonrandomized early phase studies with a relatively small number of patients enrolled. From the larger database of nonrandomized trials, we listed adverse events in specific organs/sites among patients with cancer who are treated with photons and protons to identify critical issues. The present data demonstrate dosimetric advantages of PT with favorable toxicity profiles and form the basis for comparative randomized prospective trials. A comparative analysis of 3 recently completed randomized trials for normal tissue toxicities suggests that for early stage non-small cell lung cancer, no meaningful comparison could be made between stereotactic body RT and stereotactic body PT due to low accrual (NCT01511081). In addition, for locally advanced non-small cell lung cancer, a comparison of intensity modulated RT with passive scattering PT (now largely replaced by spot-scanned intensity modulated PT), PT did not provide any benefit in normal tissue toxicity or locoregional failure over photon therapy. Finally, for locally advanced esophageal cancer, proton beam therapy provided a lower total toxicity burden but did not improve progression-free survival and quality of life (NCT01512589). The purpose of this review is to inform the limitations of current trials looking at protons and photons, considering that advances in technology, physics, and biology are a continuum, and to advocate for future trials geared toward accurate precision RT that need to be viewed as an iterative process in a defined path toward delivering optimal radiation treatment. A foundational understanding of the radiobiologic differences between protons and photons in tumor and normal tissue responses is fundamental to, and necessary for, determining the suitability of a given type of biologically optimized RT to a patient or cohort.

Medical countermeasures for radiation induced health effects: report of an Interagency Panel Session held at the NASA Human Research Program Investigator's Workshop, 26 January 2017.

An Interagency Panel Session organized by the NASA Human Research Program (HRP) Space Radiation Program Element (SRPE) was held during the NASA HRP Investigator's Workshop (IWS) in Galveston, Texas on 26 January 2017 to identify complementary research areas that will advance the testing and development of medical countermeasures (MCMs) in support of radioprotection and radiation mitigation on the ground and in space. There were several areas of common interest identified among the various participating agencies. This report provides a summary of the topics discussed by each agency along with potential areas of intersection for mutual collaboration opportunities. Common goals included repurposing of pharmaceuticals, nutraceuticals for use as radioprotectors and/or mitigators, low-dose/chronic exposure paradigms, late effects post-radiation exposure, mixed-field exposures of gamma-neutron, performance decrements, and methods to determine individual exposure levels.

Potential Molecular Targets in the Setting of Chemoradiation for Esophageal Malignancies.

Although the development of effective combined chemoradiation regimens for esophageal cancers has resulted in statistically significant survival benefits, the majority of patients treated with curative intent develop locoregional and/or distant relapse. Further improvements in disease control and survival will require the development of individualized therapy based on the knowledge of host and tumor genomics and potentially harnessing the host immune system. Although there are a number of gene targets that are amplified and proteins that are overexpressed in esophageal cancers, attempts to target several of these have not proven successful in unselected patients. Herein, we review our current state of knowledge regarding the molecular pathways implicated in esophageal carcinoma, and the available agents for targeting these pathways that may rationally be combined with standard chemoradiation, with the hope that this commentary will guide future efforts of novel combinations of therapy.

Low-Dose Radiation Therapy (LDRT) for COVID-19: Benefits or Risks?

The limited impact of treatments for COVID-19 has stimulated several phase 1 clinical trials of whole-lung low-dose radiation therapy (LDRT; 0.3-1.5 Gy) that are now progressing to phase 2 randomized trials worldwide. This novel but unconventional use of radiation to treat COVID-19 prompted the National Cancer Institute, National Council on Radiation Protection and Measurements and National Institute of Allergy and Infectious Diseases to convene a workshop involving a diverse group of experts in radiation oncology, radiobiology, virology, immunology, radiation protection and public health policy. The workshop was held to discuss the mechanistic underpinnings, rationale, and preclinical and emerging clinical studies, and to develop a general framework for use in clinical studies. Without refuting or endorsing LDRT as a treatment for COVID-19, the purpose of the workshop and this review is to provide guidance to clinicians and researchers who plan to conduct preclinical and clinical studies, given the limited available evidence on its safety and efficacy.

Development of Novel Radiosensitizers through the National Cancer Institute's Small Business Innovation Research Program.

While radiosensitizing chemotherapy has improved survival for several types of cancer, current chemoradiation regimens remain ineffective for many patients and have substantial toxicities. Given the strong need for the development of novel radiosensitizers to further improve patient outcomes, the Radiation Research Program (RRP) and the Small Business Innovation Research (SBIR) in the National Cancer Institute (NCI) issued a Request for Proposals (RFP) through the NCI SBIR Development Center's contracts pathway. We sought to determine the research outcomes for the NCI SBIR Development Center's funded proposals for the development of radiosensitizers. We identified SBIR-funded contracts and grants for the development of radiosensitizers from 2009 to 2018 using the National Institutes of Health (NIH) Reporter database. Research outcomes of the NCI SBIR Development Center-funded proposals were determined using a comprehensive internet search. We searched PubMed, clinicaltrials.gov, company websites and google.com for research articles, abstracts and posters, clinical trials, press releases and other news, related to progress in the development of funded radiosensitizers. To protect the intellectual property of the investigators and small businesses, all information obtained and reported is publicly available. The SBIR Program has funded four contracts and 11 grants for the development of novel radiosensitizers. Two companies have received phase IIb bridge awards. Overall, 50% of companies (6/12) have successfully advanced their investigational drugs into prospective clinical trials in cancer patients, and all but one company are investigating their drug in combination with radiation therapy as described in the NCI SBIR Development Center proposal. To date, only one company has initiated a randomized trial of standard of care with or without their radiosensitizer. In conclusion, the NCI SBIR Development Center has funded the development of novel radiosensitizers leading to clinical trials of novel drugs in combination with radiation therapy. Continued follow-up is needed to determine if any of these novel radiosensitizers produce improved tumor control and/or overall survival.

Radiation Biomarkers: Can Small Businesses Drive Accurate Radiation Precision Medicine?

Radiation therapy is an essential component of cancer treatment. Currently, tumor control and normal tissue complication probabilities derived from a general patient population guide radiation treatment. Its outcome could be improved if radiation biomarkers could be incorporated into approaches to treatment. A substantial number of cancer patients suffer from side effects of radiation therapy. These side effects can result in treatment interruption. Such unplanned treatment interruptions not only jeopardize anticancer treatment efficacy but also result in poor post-treatment quality-of-life. To develop and translate radiation biomarkers for clinical use, NCI's Radiation Research Program, in collaboration with the Small Business Innovation Research Development Center, funded four small businesses through the request for proposals after peer review during 2015-2019. Here, we summarize publicly available information on intellectual property rights, the status of development, ongoing clinical trials, success in obtaining financing and regulatory approval. An analysis of publicly available information indicates all four companies have completed phase I of SBIR funding and advanced to further development, validation and clinical trials with phase II SBIR funding. These biomarkers are: 1. A panel of genomic biomarkers of radiation response to predict toxicity and radioimmune response (MiraDx Inc., Los Angeles, CA); 2. A multiplex assay for single nucleotide polymorphism (SNP) biomarkers of radiation sensitivity to identify a subset of prostate cancer patients for which radiotherapy is contraindicated (L2 Diagnostics, New Haven, CT); 3. A cell-free DNA assay in blood to measure tissue damage shortly after radiation exposure (DiaCarta Inc., Richmond, CA); and 4. A metabolomic/lipidomic assay to predict late effects that adversely affect quality-of-life among patients treated with radiation for prostate cancer (Shuttle Pharmaceuticals, Rockville, MD). This work also provides a bird's eye view of the process of developing radiation biomarkers for use in radiation oncology clinics, some of the challenges and future directions.

Advancing Targeted Radionuclide Therapy Through the National Cancer Institute's Small Business Innovation Research Pathway.

The Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs of the National Cancer Institute (NCI) are congressionally mandated set-aside programs that provide research funding to for-profit small businesses for the development of innovative technologies and treatments that serve the public good. These two programs have an annual budget of $159 million (in 2017) and serve as the NCI's main engine of innovation for developing and commercializing cancer technologies. In collaboration with the NCI's Radiation Research Program, the NCI SBIR Development Center published in 2015-2017 three separate requests for proposals from small businesses for the development of systemic targeted radionuclide therapy (TRT) technologies to treat cancer. TRT combines a cytotoxic radioactive isotope with a molecularly targeted agent to produce an anticancer therapy capable of treating local or systemic disease. This article summarizes the NCI SBIR funding solicitations for the development of TRTs and the research proposals funded through them.

Decreasing the Toxicity of Radiation Therapy: Radioprotectors and Radiomitigators Being Developed by the National Cancer Institute Through Small Business Innovation Research Contracts.

PURPOSE: The use of radioprotectors and radiomitigators could improve the therapeutic index of radiation therapy. With the intention of accelerating translation of radiation-effect modulators (radioprotectors and mitigators), the Radiation Research Program and SBIR (Small Business Innovation Research) Development Center within the National Cancer Institute issued 4 Requests for Proposals (RFPs) from 2010 to 2013. Twelve SBIR contract awards in total were made in response to the 4 RFPs from September 2011 through September 2014. Here, we provide an update on the status of SBIR contract projects for the development of radiation-effect modulators. METHODS AND MATERIALS: To assess the status of research and development efforts under the 4 RFPs on radiation-effect modulators, we searched PubMed for research articles, google.com for published abstracts, clinicaltrials.gov for ongoing or completed clinical trials, and company websites for press releases and other news. All information obtained and reported here is publicly available and thus protects the intellectual property of the investigators and companies. RESULTS: Of the 12 SBIR projects funded, 5 (42%) transitioned successfully from phase 1 to phase 2 SBIR funding, and among the Fast-Track contracts, this rate was 100% (3 of 3). The Internet search identified 3 abstracts and 6 publications related to the aims of the SBIR contracts. One-third of the companies (4 of 12) have successfully launched a total of 8 clinical trials to demonstrate the safety and efficacy of their investigational agents. Two drugs are in clinical trials for their indication as a radioprotector, and 2 drugs are under evaluation for their anticancer properties (an immunomodulator and a small molecule inhibitor). CONCLUSIONS: The National Cancer Institute's SBIR has provided pivotal funding to small businesses for the development of radioprotectors and radiomitigators, which resulted in multiple early-phase clinical trials. Longer follow-up is needed to determine the full impact of these novel therapeutics that enter clinical practice.